Adjusted Employer's QUARTERLY Federal Tax Return or Claim for Refund
Form 941-X corrects a previously filed Form 941. It is filed on its own rather than as an amended version of the original return, and one 941-X corrects one quarter - correcting three quarters means three forms. The form asks the filer to choose between the adjustment process and the claim process, and that choice determines whether an overreported amount is applied against a current liability or refunded. Underreported and overreported amounts on the same quarter generally cannot be combined on one form using the claim process.
Whether you deposit monthly or semiweekly depends on your lookback period, not on this form. Publication 15 (Circular E) sets the rule, and it is worth checking each year - the schedule can change when your liability does.
IRS Publication 15No. One form per quarter corrected. Three wrong quarters means three separate 941-X forms.
Yes - the period of limitations applies, and it differs depending on whether you are correcting an underreported or an overreported amount. Check the form's instructions against the specific quarter before assuming a claim is still open.